Quantification of Aerosol Particle Concentrations During Endoscopic Sinonasal Surgery in the Operating Room

Abstract

Background: Recent indirect evidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission during endoscopic endonasal procedures has highlighted the dearth of knowledge surrounding aerosol generation with these procedures. As we adapt to function in the era of Coronavirus Disease 2019 (COVID-19) a better understanding of how surgical techniques generate potentially infectious aerosolized particles will enhance the safety of operating room (OR) staff and learners.

Objective: To provide greater understanding of possible SARS-CoV-2 exposure risk during endonasal surgeries by quantifying increases in airborne particle concentrations during endoscopic sinonasal surgery.

Methods: Aerosol concentrations were measured during live-patient endoscopic endonasal surgeries in ORs with an optical particle sizer. Measurements were taken throughout the procedure at six time points: 1) before patient entered the OR, 2) before pre-incision timeout during OR setup, 3) during cold instrumentation with suction, 4) during microdebrider use, 5) during drill use and, 6) at the end of the case prior to extubation. Measurements were taken at three different OR position: surgeon, circulating nurse, and anesthesia provider.

Results: Significant increases in airborne particle concentration were measured at the surgeon position with both the microdebrider (p = 0.001) and drill (p = 0.001), but not for cold instrumentation with suction (p = 0.340). Particle concentration did not significantly increase at the anesthesia position or the circulator position with any form of instrumentation. Overall, the surgeon position had a mean increase in particle concentration of 2445 particles/ft3 (95% CI 881 to 3955; p = 0.001) during drill use and 1825 particles/ft3 (95% CI 641 to 3009; p = 0.001) during microdebrider use.

Conclusion: Drilling and microdebrider use during endonasal surgery in a standard operating room is associated with a significant increase in airborne particle concentrations. Fortunately, this increase in aerosol concentration is localized to the area of the operating surgeon, with no detectable increase in aerosol particles at other OR positions.

Keywords: COVID-19; SARS-CoV-2; aerosolization; airborne particles; endoscopic sinus surgery.

Figure 1.

Distance from operative field (nasal tip) to the surgeon, anesthesia, or circulator position. (a) Schematic of standard operating room layout. Surgeon position was an average of 39 cm from the nasal tip. Anesthesia position was an average of 264 cm from the nasal tip and the circulator workstation position was an average of 319 cm from the field. (b) The range for the surgeon position was 34 cm to 42 cm. The range for the circulator position was 212 cm to 400 cm and the range for the anesthesia position was 219 to 310 cm depending on the specific operating room that the case occurred.

Figure 2.

Changes in mean particle concentration particles/ft³ (p/ft³) exposure for different OR personnel before and after surgical instrument. All pre-instrumentation values normalized to zero to illustrate changes in concentration. (a) The mean difference in particle concentration before and after cold instrumentation with suction was 716 p/ft³ at the surgeon position, −112 p/ft³ at the circulator workstation position, and –398 p/ft³ at the anesthesia provider position. (b) Ex vivo aerosol concentrations measured after progressively longer durations of use, demonstrated comparable aerosol concentrations when compared at the operator position. (c) The mean difference in particle concentration before and after microdebrider use was 1825 (p = 0.001) at the surgeon position, 40 p/ft³ at the circulator workstation position, and −935 p/ft³ at the anesthesia provider position. (d) The mean difference in particle concentration before and after drill use was 2418 p/ft³ (p = 0.001) at the surgeon position, –34 p/ft³ at the circulator workstation position, and −1690 p/ft³ at the anesthesia provider position. 95% confidence intervals designated by black bars.

Figure 3.

Difference in mean particle concentrations during drill use compared to microdebrider use. No significant difference (p = 0.59) found in mean aerosol concentration for the microdebrider at 1825 particles/ft³ (95% CI 508 to 3141) compared to the mean aerosol concentration for the drill at 2445 particles/ft³ (95% CI 595 to 4294).

Figure 4.

Distribution of mean particle concentration by measured particle size. Total of 133 sample measurements were taken with a mean of 1205 particles measuring 0.3 µm in diameter, 414 particles at 0.5 µm in diameter, 78 particles at 1.0 µm in diameter, 12 particles at 2.5 µm in diameter, 2 particles at 5.0 µm in diameter, and a mean of 1 particle at 10 µm in diameter.